1. Field of the Invention
The present invention relates to a two-speed toy car and track assembly and more particularly to a two-speed toy car and track assembly wherein the speed of a toy car travelling on a track is changed by reversing the polarity of direct current supplied to a motor incorporated in the car.
2. Brief Description of the Prior Art
The prior art is well aware of toy cars adapted for travelling on a predetermined track. More particularly, the prior art is well aware of toy cars which incorporate an electric motor receiving a supply of current from a track assembly. Toy cars described in U.S. Pat. Nos. 4,163,341 and 4,136,485 generally reflect the current state of the art relating to electric powered toy cars adapted for travelling on a track.
As is well appreciated by those skilled in the art, a toy car travelling on a track, particularly one which is used for simulated racing and which is expected to negotiate sharp turns at relatively high speeds, must have significant traction relative to the surface of the track. Means employed in the prior art for providing relatively high traction include the use of wide, high friction driving wheels, increasing the weight of the car, and providing a magnetic force which attracts the car to the track surface.
The relatively large traction of the toy car to the surface of the track, such as the one which may be achieved by the aforesaid magnetic attracting force, however, creates a difficulty in controlling the speed of the toy car. More particularly, prior art toy car track assemblies typically utilize a continuously variable resistive load placed in the path of the current supplied to the car as a means for controlling the speed of the car at the option of a player. However, when the traction between the track surface and the car is relatively large, it is difficult and therefore economically undesirable to provide an electric motor which is capable of responding to an electric power input varying across a wide range. It is especially difficult and therefore economically undesirable to provide an electric motor for a toy car which is capable of propelling the toy car on a high traction surface without stalling when the applied voltage is deliberately set at a low value.
Accordingly, the present invention is directed to a toy car and track assembly combination wherein the car has good traction on the track surface and wherein the speed of the car may be controlled by changing a gear reduction ratio in the drive train of the car.
The car track assembly combination of the present invention is hereinafter described in detail. For the purpose of describing the background of the present invention, it is however deemed necessary to describe briefly a prior art toy car which in its construction bears some resemblance to the toy car of the present invention.
Thus, a toy car which has been commercially available in the United States includes a steering mechanism which is responsive to a change in the polarity of the direct current supplied to the car by a pair of electrically conducting rails incorporated in a track. In order to avoid reversal of direction of travel of the car each time the polarity of the current in the rails is changed, a pinion gear mounted to an output shaft of the motor of the car is connected to two crown gears. The crown gears are driven by the pinion gear to rotate in opposite direction relative to one another, and each crown gear is provided with a one-way clutch. The one-way clutches are operatively connected with an axle of two driven rear wheels of the toy car. Each one-way clutch is designed to engage and drive the axle only when the respective crown gear rotates in a direction which, when transferred to the axle, would result in a forward motion of the vehicle. In other words, as the output shaft of the electric motor rotates in a first direction, only the first crown gear engages the axle and drives the vehicle forward. When rotation of the output shaft of the motor is reversed, the second crown gear engages the axle and still drives the car forward. In this manner a reversal of the polarity of the current supplied to the motor in the course of steering the car has no net effect on the rear driving wheels of the car.
In contrast to the above described prior art toy car, the toy car of the present invention utilizes changes in the polarity of the current supplied to the electric motor of the car to affect a change in the speed of travel of the car.